JP2009173926A - Method to improve cold flow resistance of polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method to improve cold flow resistance of a polymer, by using an acetal or ketal of a specified alditol. <P>SOLUTION: A method for preparing a polymeric composition includes a process for preparing polymer cement containing the polymer and a solvent, a process for introducing the acetal or ketal of an alditol to the polymer cement, and a process for isolating at least a portion of the polymer and the acetal or ketal of an alditol from the solvent to obtain the polymeric composition containing the polymer and the acetal or ketal of an alditol. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

(Claiming priority)
This application claims the benefit of US Provisional Application No. 61 / 017,913, filed December 31, 2007, which is incorporated herein by reference.

  One or more embodiments of the present invention relate to a method for improving the cold flow resistance of a polymer by using specific alditol acetals and ketals.

  Certain polymers, such as polydiene elastomers, exhibit cold flow at standard conditions. That is, the polymer flows by its own weight, which creates problems when attempting to transport or store the polymer. Therefore, it is desirable to prevent the occurrence of cold flow by improving the cold flow resistance of the polymer.

  One solution used in the art is polymer coupling. For example, linear polydienes such as polydienes produced by anionic polymerization or coordination catalysts are coupled with the compound. Coupling agents help to improve cold flow resistance, but do not necessarily help to provide desirable tire properties.

  Thus, in the field of manufacturing tires, particularly tire treads, functionalized polymers are advantageously used to improve properties such as hysteresis loss. These functionalized polymers are often produced by stopping polymer chain growth with a functionalizing agent that imparts a functional group to the end of the polymer chain.

  Unfortunately, the functionalizing agent used to stop the polymer and give the tire advantageous properties does not necessarily help to provide the polymer with cold flow resistance. In addition, coupling agents that improve cold flow resistance often react with polymer chains, but are incompatible with functionalizing agents. Therefore, it is not always possible to achieve good cold flow resistance and desirable tire characteristics by combining a functionalizing agent and a coupling agent.

  There remains a need for functionalized polymers, and in fact functionalized polymers with a high degree of functionality are desired, and the use of coupling agents that compete with the functionalizing agent can detrimental for this purpose. Therefore, it is necessary to improve the cold flow resistance by means other than the coupling reaction.

  One or more embodiments of the present invention include the steps of providing a polymer cement comprising a polymer and a solvent, introducing an alditol acetal or ketal into the polymer cement, and at least one of the polymer and alditol acetal or ketal from the solvent. Separating the parts to obtain a polymer composition comprising a polymer and an acetal or ketal of alditol, and a method for producing a polymer composition.

  Another embodiment provides a method for producing a polymer composition comprising the steps of providing a polymer cement and introducing dibenzylidene sorbitol into the polymer cement.

  Yet another embodiment provides a polymer composition comprising an elastomer and a sorbitol derivative.

FIG. 1 shows a comparison of the kinematic viscosity coefficient (η) of SBR and SBR containing 1 and 3 wt% DBS using 2% strain and frequency sweep at 25 ° C. FIG. 2 is a graph of RPA stress relaxation data (50 ° C. at 100% strain) for SBR and SBR treated with 0, 1 and 3 wt% DBS.

I. INTRODUCTION It has been unexpectedly discovered that alditol acetals or ketals can be used to improve the cold flow properties of an elastomer without adversely affecting the properties or use of the elastomer. In certain embodiments, it has been found that these alditol acetals or ketals are useful in improving the cold flow properties of functionalized elastomers. In one or more embodiments, the acetal or ketal of alditol has surprisingly achieved improved cold flow resistance of the polymer without adversely affecting the ability to mix or process the polymer. That is, the transport and storage of certain polymers in which the acetals or ketals of alditols or their reaction or interaction products in the polymer are temperature and / or shear dependent and exhibit low resistance to cold flow. And surprisingly found to be very advantageous for formulation. A polymer composition produced from the elastomer composition of one or more embodiments of the present invention was also produced in the same manner, but with the same vulcanization characteristics and the same Mooney as the composition containing no alditol acetal or ketal. Shows viscosity and similar kinetic properties.

II. Alditol Acetals or Ketals In one or more embodiments, alditol acetals or ketals include mono-, di-, or tri-acetals or ketals of alditols. In these or other embodiments, acetals or ketals of alditols include reaction products of alditols with aldehydes, ketones or both aldehydes and ketones. These reactions are known in the art. For example, alditols and aldehydes are described in U.S. Pat. Nos. 4,429,140 and 5,106,999, U.S. Patent Publication Nos. 2007/0299256 and 2007/0249850, and International Publication No. 1992/000301. The reaction can be carried out in the presence of the described acid catalyst, the entire contents of these documents being incorporated herein by reference. For example, alditol ketals are alditols and dimethoxyalkanes as taught in Smith, Michael B .; March, Jerry; March's Advanced Organic Chemistry, 5th Ed .; John Wiley & Sons, Inc: New York, 2001. Can be made to react.

（Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５、Ｒ^６、Ｒ^７及びＲ^８は、それぞれ独立して水素原子または１価の有機基であり、ｎは０、１又は２である）
によって定義される化合物が挙げられる。 In one or more embodiments, alditols can also be referred to as substituted or unsubstituted alditols, such alditols having the formula:

(R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom or a monovalent organic group, and n is 0, 1 or 2. )
The compound defined by is mentioned.

  In one or more embodiments, the monovalent organic group is not particularly limited, but is an alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an alkenyl group, a cycloalkenyl group, a substituted cycloalkenyl group, an aryl group, an allyl group. , Substituted aryl groups, aralkyl groups, hydrocarbyl groups such as alkaryl groups and alkynyl groups, or substituted hydrocarbyl groups. Substituted hydrocarbyl groups include hydrocarbyl groups in which one or more hydrogen atoms are substituted with a substituent such as an alkyl group. In one or more embodiments, these groups may contain from a minimum number of carbon atoms suitable to form one or groups up to 20 carbon atoms. These hydrocarbyl groups are not particularly limited, but may contain heteroatoms such as nitrogen atom, boron atom, oxygen atom, silicon atom, sulfur atom and phosphorus atom.

In certain embodiments, R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁸ are each independently a hydrogen atom or a monovalent organic group having 2 or less carbon atoms, and R ¹ And R ⁷ each independently represents a hydrogen atom or a monovalent organic group. In certain embodiments, R ¹ and R ⁷ are each independently a hydrogen atom, alkenyl group, alkyl group, alkoxy group, hydroxylalkyl group, or alkyl halide group.

  Specific examples of alditol include, but are not limited to, sorbitol, xylitol, allyl-sorbitol, propyl-sorbitol, 1-methyl-2-propenyl sorbitol, allyl-xylitol, and propyl-xylitol.

In one or more embodiments, the aldehyde includes a compound represented by the formula: R ⁹ —C (O) H (R ⁹ is a monovalent organic group). In certain embodiments, R ⁹ is at least 3 carbon atoms, in other embodiments at least 6 carbon atoms, in other embodiments, from at least 9 carbon atoms up to 20 carbon atoms. An acyclic hydrocarbyl group or a substituted hydrocarbyl group, wherein the term substitution refers to the substitution of one or more hydrogen atoms attached to a carbon atom with a monovalent organic group. In other embodiments, R ⁹ is a cyclic hydrocarbyl group or substituent containing 6 carbon atoms, in other embodiments at least 8 carbon atoms, and in other embodiments at least 10 carbon atoms in the ring. A cyclic hydrocarbyl group. In certain embodiments, R ⁹ is a heterocyclic group or a substituted heterocyclic group. In still other embodiments, R ⁹ is an aromatic group or a substituted aromatic group. In still other embodiments, R ⁹ is a heteroaromatic group or a substituted heteroaromatic group.

  Examples of aldehydes include formaldehyde, acetaldehyde, propanal, butanal, pentanal, hexanal, heptanal, octanal, nonanal, decanal, dodecanal, cyclohexane carboxaldehyde, cyclopeptane carboxaldehyde, cyclooctane carboxaldehyde, cyclodecane carboxaldehyde, cyclohexane Examples include, but are not limited to, dodecane carboxaldehyde, benzaldehyde, 2-methoxybenzaldehyde, 4-diethylaminobenzaldehyde, trans-cinnamic aldehyde, and mixtures thereof.

（Ｒ^１０、Ｒ^１１、Ｒ^１２、Ｒ^１３及びＲ^１４は、それぞれ独立して水素原子又は１価の有機基であるか、又はＲ^１０、Ｒ^１１、Ｒ^１２、Ｒ^１３及びＲ^１４の２つもしくは３つ以上が結合して２価の有機基を形成している）で示されるものであってもよい、ベンズアルデヒド又は置換ベンズアルデヒドである。 In certain embodiments, the aldehyde has the following formula:

(R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently a hydrogen atom or a monovalent organic group, or 2 of R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ . Benzaldehyde or substituted benzaldehyde, which may be represented by the following formula:

  In one or a plurality of embodiments, the divalent organic group is not particularly limited, but an alkylene group, a cycloalkylene group, a substituted alkylene group, a substituted cycloalkylene group, an alkenylene group, a cycloalkenylene group, a substituted alkenylene group, a substituted cyclohexane Examples include hydrocarbylene groups or substituted hydrocarbylene groups such as alkenylene groups, arylene groups, and substituted arylene groups. The substituted hydrocarbylene group includes a hydrocarbylene group in which one or more hydrogen atoms are substituted with a substituent such as an alkyl group. In one or more embodiments, these groups may contain from 2 or up to 20 carbon atoms suitable to form 2 or groups. The divalent organic group is not particularly limited, but may contain one or a plurality of heteroatoms such as a nitrogen atom, an oxygen atom, a boron atom, a silicon atom, a sulfur atom, and a phosphorus atom.

  Examples of substituted benzaldehydes include 4-ethylbenzaldehyde, 4-isobutylbenzaldehyde, 4-fluoro-3-methylbenzaldehyde, 3-methylbenzaldehyde, 4-propylbenzaldehyde, 4-butylbenzaldehyde, 4-methoxybenzaldehyde, 3-chlorobenzaldehyde, 3 , 4-dimethylbenzaldehyde, 3,5-difluorobenzaldehyde, 3-fluorobenzaldehyde, 4-fluorobenzaldehyde, 3-bromo-4-fluorobenzaldehyde, 3-methyl-4-methoxybenzaldehyde, 2,4,5-trimethylbenzaldehyde, 4-chloro-3-fluorobenzaldehyde, 4-methylbenzaldehyde, 3-bromobenzaldehyde, 4-methoxybenzaldehyde, 3,4- Chlorobenzaldehyde, 4-fluoro-3,5-dimethylbenzaldehyde, 2,4-dimethylbenzaldehyde, 4-bromobenzaldehyde, 3-ethoxybenzaldehyde, 4-allyloxybenzaldehyde, 3,5-dimethylbenzaldehyde, 4-chlorobenzaldehyde, 3 -Methoxybenzaldehyde, 4- (trifluoromethyl) benzaldehyde, 2-naphthaldehyde, 4-isopropylbenzaldehyde, 3,4-dimethoxy-benzaldehyde, 3-bromo-4-ethoxybenzaldehyde, piperonal, 3,4-dimethoxy-benzaldehyde, Examples include, but are not limited to, 4-carboxybenzaldehyde, 3-hex-1-ynylbenzaldehyde, and 2-chlorobenzaldehyde.

In one or more embodiments, the ketone has the formula: R ⁹ —C (O) —R ¹⁵ (wherein R ¹⁵ and R ⁹ are each independently a monovalent organic group, or R ¹⁵ and R ⁹ is bonded to form a divalent organic group). In certain embodiments, at least one of R ¹⁵ and R ⁹ is at least 3 carbon atoms, in other embodiments at least 6 carbon atoms, in other embodiments from at least 9 carbon atoms up to 20 An acyclic hydrocarbyl group or substituted hydrocarbyl group having up to carbon atoms, wherein the term substitution is the substitution of one or more hydrogen atoms attached to a carbon atom with a monovalent organic group Point to. In other embodiments, at least one of R ¹⁵ and R ⁹ comprises in the ring 6 carbon atoms, in other embodiments at least 8 carbon atoms, in other embodiments at least 10 carbon atoms. A cyclic hydrocarbyl group or a substituted cyclic hydrocarbyl group. In certain embodiments, at least one of R ¹⁵ and R ⁹ is a heterocyclic group or a substituted heterocyclic group. In still other embodiments, at least one of R ¹⁵ and R ⁹ is an aromatic group or a substituted aromatic group. In still other embodiments, at least one of R ¹⁵ and R ⁹ is a heteroaromatic group or a substituted heteroaromatic group.

  Examples of ketones include acetone, propanone, 2-butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, 2-heptanone, 4-heptanone, 2-octanone, 4-octanone, 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone, 5-decanone, acetophenone, benzophenone, 4,4′-bis (diethylamino) benzophenone, cyclobutanone, cyclohexanone, cycloheptanone, cyclooctanone, cyclododecanone, and their Although a mixture is mentioned, it is not specifically limited.

（Ｒ^２０、Ｒ^２１、Ｒ^２３、Ｒ^２４、Ｒ^２５、Ｒ^２６、Ｒ^２７、Ｒ^２８、Ｒ^２９、Ｒ^３０及びＲ^３１は、それぞれ独立して水素原子又は１価の有機基であるか、又はＲ^２０及びＲ^２１及び／又はＲ^２２及びＲ^２3が結合して２価の有機基を形成しており、ｎは、０、１又は２である）によって定義することができる。特定の実施態様において、Ｒ^２０及びＲ^２２は１価の有機基であり、Ｒ^２１及びＲ^２３は水素原子である。これらの又は他の実施態様において、Ｒ^２５は１価の有機基であり、Ｒ^２４、Ｒ^２６、Ｒ^２７、Ｒ^２８、Ｒ^２９、Ｒ^３０及びＲ^３１は水素原子である。 In one or more embodiments, the acetal or ketal of alditol has the following formula:

(R ²⁰ , R ²¹ , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ are each independently a hydrogen atom or a monovalent organic group. Or R ²⁰ and R ²¹ and / or R ²² and R ²³ are bonded to form a divalent organic group, and n is 0, 1 or 2. In a particular embodiment, R ²⁰ and R ²² are monovalent organic groups and R ²¹ and R ²³ are hydrogen atoms. In these or other embodiments, R ²⁵ is a monovalent organic group and R ²⁴ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ are hydrogen atoms.

（式中、Ｒ^２１、Ｒ^２３、Ｒ^２４、Ｒ^２５、Ｒ^２６、Ｒ^２７、Ｒ^２８、Ｒ^２９、Ｒ^３０、Ｒ^３１、Ｒ^４０、Ｒ^４１、Ｒ^４２、Ｒ^４３、Ｒ^４４、Ｒ^４５、Ｒ^４６、Ｒ^４７、Ｒ^４８及びＲ^４９は、それぞれ独立して水素原子又は１価の有機基であるか、又はＲ^４０、Ｒ^４１、Ｒ^４２、Ｒ^４３、Ｒ^４４、Ｒ^４５、Ｒ^４６、Ｒ^４７、Ｒ^４８及びＲ^４９のうち２つ又は３つ以上が結合して２価の有機基を形成しており、ｎは、０、１又は２である）によって定義することができる。 In one or other embodiments, R ²⁰ and R ²² are aromatic groups, and certain embodiments have the formula:

(In the formula, R ²¹ , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , R ³¹ , R ⁴⁰ , R ⁴¹ , R ⁴² , R ⁴³ , R ⁴⁴ , R ⁴⁵ , R ⁴⁶ , R ⁴⁷ , R ⁴⁸ and R ⁴⁹ are each independently a hydrogen atom or a monovalent organic group, or R ⁴⁰ , R ⁴¹ , R ⁴² , R ⁴³ , R ⁴⁴ , R ⁴⁵ , 2 or 3 or more of R ⁴⁶ , R ⁴⁷ , R ⁴⁸ and R ⁴⁹ are bonded to form a divalent organic group, and n is 0, 1 or 2. it can.

  In one or more embodiments, examples of alditol acetals include dimethylidene sorbitol, dibenzylidene sorbitol (DBS), di (alkylbenzylidene) sorbitol, 1,3-O-2,4-bis (3,4- Dimethylbenzylidene) sorbitol, 1,3,2,4-bis (4-ethylbenzylidene) -1-allyl-sorbitol, 1,3,2,4-bis (3′-methyl-4′-fluoro-benzylidene)- 1-propyl-sorbitol, 1,3,2,4-bis (5 ′, 6 ′, 7 ′, 8′-tetrahydro-2-naphthaldehydebenzylidene) -1-allyl-xylitol, bis-1,3,2 , 4- (3 ′, 4′-dimethylbenzylidene) -1 ″ -methyl-2 ″ -propyl-sorbitol and 1,3,2,4-bis (3 ′ 4'-dimethyl benzylidene) -1-propyl - xylitol.

III. Polymers to be treated In one or more embodiments, polymers incorporating alditol acetals or ketals according to the present invention exhibit low resistance to cold flow and hence technical problems during storage and transport. There is a polymer.

  In one or more embodiments, these polymers can be characterized by unfavorable cold flow as determined by using ASTM standard cold flow measurements or derivatives thereof. These tests are known to those skilled in the art. For example, the cold flow due to gravity can generally be determined according to the following method, which can be referred to as a standard test. A sample of the polymer to be tested is molded into a cylindrical shape having a diameter of about 10 mm and a height of about 13 mm. The cylinder is placed on one of its circular bottoms and left in place for 28 days, after which the cylinder height is measured. Alternatively, these samples can be placed under a weight that mimics the force drawn on the polymer under the weight of an additional bale of rubber that can be stacked on the bottom bale.

  In other embodiments, similar tests can be performed in an accelerated manner using a Scott tester. This can be determined by the following method, which can be referred to as an accelerated test. A 40 mm × 13 mm cylinder is placed on one of the bottoms of the cylinder and a weight such as a mass of 5000 grams is placed on the cylinder for 30 minutes, after which the height of the cylinder is measured.

  In one or more embodiments, polymers that can be conveniently processed according to one or more embodiments of the present invention include, prior to processing according to the present invention, at room temperature of a 13 mm cylindrical sample of polymer. 7 mm or less after 28 days of standard cold testing (ie, cold flow analysis by gravity), in other embodiments 6 mm or less, in other embodiments 5 mm or less, in other embodiments 4 mm or less, other Embodiments include polymers characterized by cold flow as indicated by a sample height of 3 mm or less.

  In these or other embodiments, polymers that can be conveniently processed in accordance with one or more embodiments of the present invention include accelerated 13 mm cylindrical samples of polymer prior to processing according to the present invention. 7 mm or less after performing a cold test (ie, cold flow analysis with accelerated gravity using a Scott tester), 6 mm or less in other embodiments, 5 mm or less in other embodiments, 4 mm or less in other embodiments In other embodiments, mention may be made of polymers characterized by a cold flow indicated by a sample height of 3 mm or less.

  In one or more embodiments, polymers incorporating alditol acetals or ketals according to the present invention include elastomers that are polymers that can be vulcanized to form vulcanizates that exhibit rubber-like elasticity. In one or more embodiments, the elastomer is unsaturated. In one or more embodiments, the elastomer is 20 ° C. or lower, in other embodiments 10 ° C. or lower, in other embodiments 0 ° C. or lower, in other embodiments −10 ° C. or lower, in other embodiments −20 In other embodiments, it has a glass transition temperature (Tg) of -30 ° C or lower.

  In one or more embodiments, polymers incorporating alditol acetals or ketals according to the present invention include linear molecules. In other embodiments, the polymer is substantially linear or contains only some degree of branching.

  In one or more embodiments, polymers incorporating alditol acetals or ketals according to the present invention include natural and / or synthetic elastomers. In one or more embodiments, the elastomer includes a polymer that can be crosslinked or vulcanized to form a cured compound (also known as a vulcanizate) that exhibits rubbery elasticity. Synthetic elastomers may be those obtained from the polymerization of conjugated diene monomers. These conjugated diene monomers may be copolymerized with other monomers such as vinyl aromatic monomers. In one or more embodiments, the conjugated diene monomer includes 1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl- Examples include 1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, and 2,4-hexadiene. In one or more embodiments, the vinyl aromatic monomer includes styrene, α-methyl styrene, vinyl toluene, vinyl naphthalene, p-butyl styrene, and t-butyl styrene. Other rubbery elastomers may be obtained by polymerizing ethylene with one or more α-olefins and optionally one or more diene monomers.

  Useful rubbery elastomers include natural rubber, synthetic polyisoprene, polybutadiene, polyisobutylene-co-isoprene, neoprene, poly (ethylene-co-propylene), poly (styrene-co-butadiene), poly (styrene-co-). Isoprene), poly (styrene-co-isoprene-co-butadiene), poly (isoprene-co-butadiene), poly (ethylene-co-propylene-co-diene), polysulfide rubber, acrylic rubber, urethane rubber, silicone rubber , Epichlorohydrin rubber, and mixtures thereof. These elastomers can have a myriad of macromonomer structures including linear, branched and star shaped.

  In one or more embodiments, useful elastomers are 500 kg / mol or less, in other embodiments 400 kg / mol or less, in other embodiments 300 kg / mol or less, in other embodiments 250 kg / mol or less, other It may have a number average molecular weight (Mn) of 200 kg / mol or less in other embodiments, 150 kg / mol or less in other embodiments, and 125 kg / mol or less in other embodiments. In these or other embodiments, the elastomer has a number average molecular weight of at least 25 kg / mol, in other embodiments at least 50 kg / mol, in other embodiments at least 75 kg / mol, in other embodiments at least 100 kg / mol. You may have. In these or other embodiments, the molecular weight distribution (Mn / Mw) of the elastomer is 5.5 or less, in other embodiments 4.5 or less, in other embodiments 4.0 or less, in other embodiments 3.5 or less, in other embodiments 2.5 or less, and in other embodiments 2.0 or less. As known in the art, Mn (number average molecular weight) and Mw (weight average molecular weight) are calibrated by polystyrene standards and adjusted to the Mark-Houwink constant for the polymer in question. It can be determined using graphy (GPC).

  In one or more embodiments, the elastomer is a homopolymer, and in other embodiments, the elastomer is a copolymer, which is referred to as a polymer having two or more chemically distinguishable polymer units. , Can be called mer units. In one or more embodiments, the mer units of the polymer may be cis, trans or vinyl.

  In certain embodiments, the elastomer is about 60% or more, in other embodiments about 75% or more, in other embodiments about 90% or more, and in other embodiments about 95% or more cis-1. , A polydiene having a 4-bond content. Also, these elastomers have a 1,2-bond content (ie vinyl content) of about 7% or less, in other embodiments 5% or less, in other embodiments 2% or less, and in other embodiments 1% or less. You may have. The cis-1,4-bond content and 1,2-bond content can be determined by infrared spectroscopy. The number average molecular weight (Mn) of these polydienes is determined from about 25,000 to about 200, determined using gel permeation chromatography (GPC) calibrated with polystyrene standards and Mark-Houwink constants for the polymers of interest. 000, in other embodiments from about 30,000 to about 150,000, and in other embodiments from about 50,000 to about 120,000. The polydispersity of these polydienes may be from about 1.5 to about 5.0, and in other embodiments from about 2.0 to about 4.0. Examples of high cis-polydienes include cis-1,4-polybutadiene, cis-1,4-polyisoprene and cis 1,4-poly (butadiene-co-isoprene).

  In one or more embodiments, elastomers include medium cis or low cis polydienes (or polydiene copolymers), including those produced by anionic polymerization techniques. These elastomers have a cis content of from about 10% to about 70%, in other embodiments from about 15% to about 60%, and in other embodiments from about 20% to about 50%, the percentage being cis Based on the number of diene mer units in the structure versus the total number of diene mer units. These elastomers also have a 1,2-bond content (ie, vinyl) of about 10% to about 60%, in other embodiments about 15% to about 50%, and in other embodiments about 20% to about 45%. The percentage is based on the number of diene mer units in the vinyl structure versus the total number of diene mer units. The equilibrium of the diene units may be in a trans-1,4-bond structure.

  In certain embodiments, the elastomer includes a random copolymer of butadiene, styrene, and optionally isoprene. In other embodiments, the elastomer is a block copolymer of polybutadiene, polystyrene, and optionally polyisoprene. In certain embodiments, the elastomer is hydrogenated or partially hydrogenated.

  In one or more embodiments, the elastomer includes polybutadiene, functionalized polyisoprene, functionalized poly (styrene-co-butadiene), functionalized poly (styrene-co-butadiene-co-isoprene), functionalized poly (isoprene). -Co-styrene) and an anionically polymerized polymer selected from the group consisting of functionalized poly (butadiene-co-isoprene). The number average molecular weight of these polymers is determined from about 25,000 to about 1,000,000 determined using gel permeation chromatography (GPC) calibrated with polystyrene standards and Mark-Houwink constants for that polymer. , In other embodiments from about 50,000 to about 500,000, and in other embodiments from about 100,000 to about 300,000. The polydispersity of these polymers may be from about 1.0 to about 3.0, and in other embodiments from about 1.1 to about 2.0.

  In one or more embodiments, synthetic elastomers include functionalized elastomers. In one or more embodiments, the functionalized elastomer includes at least one functional group. In one or more embodiments, the functional group is a group or substituent that is distinguishable from the main portion of the polymer chain. In certain embodiments, the functional group includes a heteroatom. In certain embodiments, the functional group can be attached to other polymer chains (stretched and / or unstretched) or other polymers capable of binding to a polymer such as a reinforcing filler (eg, carbon black). It may be reactive or interact with the components. In certain embodiments, the functional group comprises a group attached to the polymer chain, and the hysteresis loss at 50 ° C. of the carbon black filled vulcanizate made from the functionalized polymer is similar to that made from the non-functionalized polymer. Reduced compared to carbon black filled vulcanizate. In one or more embodiments, this reduction in hysteresis loss is at least 5%, in other embodiments at least 10%, and in other embodiments at least 15%.

  In one or more embodiments, the functionalized elastomer includes a functional group located at the end of the polymer chain. In certain embodiments, the functional group may be located at the tip of the polymer, which is the beginning of the polymer or the end of the polymer where polymerization of the polymer begins. In other embodiments, the functional group may be located at the end of the polymer, which is the end of the polymer where polymerization of the polymer stops. In certain embodiments, the functionalized elastomer comprises both tip and end functionalization, i.e., the polymer has at least one functional group located at the end of the polymer chain and at least one located at the end of the polymer chain. Contains species functional groups.

  Techniques useful for producing functionalized elastomers are well known in the art. For example, these functional groups can be added during synthesis of the elastomer or by grafting to the elastomer.

  In one embodiment, the elastomer is synthesized using anionic polymerization techniques. As is known in the art, an initiator containing a functional group can be used to produce a polymer having a functional group located at the tip of the polymer chain. For example, there are initiators containing cyclic amino groups that confer cyclic amine functionality to the polymer. Examples of these initiators include lithiohexamethylene disclosed in US Pat. Nos. 6,080,835, 5,786,441, 6,025,450, and 6,046,288. Imines, which are incorporated herein by reference. In another embodiment, the elastomer is synthesized using an anionic initiator that includes at least one tin atom. These compounds, such as tin-lithium initiators, are believed to incorporate a tin atom at the end of the polymer chain. An example is lithium tributyltin disclosed in US Pat. No. 5,268,439, which is incorporated herein by reference. In yet another embodiment, using an initiator that is a dithioacetal as disclosed in US Pat. No. 7,153,919, US Publication Nos. 2006/0264590 and 2006/0264589. , Heterocyclic groups can be incorporated at the ends of the polymer chains, and these documents are incorporated herein by reference. Yet another is disclosed in US Pat. No. 7,335,712, which is incorporated herein by reference.

In yet another embodiment, the anionically polymerized elastomer is terminated with a coupling agent or terminator that provides end functionality at the end of the polymer, with or without tip functionalization. Useful compounds that can be used to couple or functionalize the ends of the living polymer are not particularly limited, but include the formula: R _n MX _{4-n where} R is an organic group, M is silicon or tin, X is a halogen atom, and n is a number from 0 to 3). Preferably, R is a simple alkyl group having 1 to about 10 carbon atoms. Examples of compounds include SnCl ₄ , R ₂ SnCl ₂ , and RSnCl ₃ described in US Pat. No. 5,332,810, which is incorporated herein by reference. Other compounds that can be used alone or in conjunction with the tin or silicon compounds include metal halides, metalloid halides, alkoxysilanes, imine-containing compounds, esters, ester-carboxylate metal complexes, alkyl esters. Examples include carboxylate metal complexes, aldehydes or ketones, amides, isocyanates, isothiocyanates, imines and epoxides.

  In yet another embodiment, an elastomer synthesized with a coordination catalyst, such as a lanthanide-based catalyst system, is terminated with a coupling agent or terminator that imparts terminal functionality to the polymer. Useful coupling agents or functionalizing agents include those described above in International Application Nos. PCT / US00 / 30743 and PCT / US00 / 30875, which are incorporated herein by reference. In one or more embodiments, suitable functionalizing agents include compounds containing groups such as ketone groups, aldehyde groups, amide groups, ester groups, imidazolidinone groups, isocyanate groups, and isothiocyanate groups. . Examples of these compounds are disclosed in US Publication Nos. 2006/0004131 A1, 2006/0025539 A1, 2006/0030677 A1, and 2004/0147694 A1, which are incorporated herein by reference. Other examples of functionalizing agents include azine compounds described in US Patent Application No. 11 / 640,711, hydrobenzamide compounds described in US Patent Application No. 11 / 710,713, US Patent Application No. 11 / 710,845 and the protected oxime compounds described in US patent application Ser. No. 60 / 875,484, all of which are incorporated herein by reference. Still other are U.S. Pat. Nos. 4,906,706, 4,990,573, 5,064,910, 5,567,784, and 5,844,050, 6,992,147, 6,977,281, U.S. Published Patent No. 2006/0004131 A1, JP-A-05-051406, JP-A-05-059103, JP-A-10-306113, and JP-A-10-306113 No. 035633, which are incorporated herein by reference. Useful functionalizing agents that can be used to couple reactive polymer chains, which can also be referred to as coupling agents, include, but are not limited to, metal halides such as tin tetrachloride. Metal halides, metalloid halides such as silicon tetrachloride, metal complexes of ester carboxylates such as dioctyltin bis (octyl maleate), alkoxysilanes such as tetraethylorthosilicate, and alkoxytin compounds such as tetraethoxytin Including any known in the art. Coupling agents can be used alone or in combination with other functionalizing agents. Combinations of functionalizing agents may be used in any molar ratio.

IV. Polymer cement A. Solvent In one or more embodiments, an acetal or ketal of alditol is introduced into the treated polymer in the polymer cement. In one or more embodiments, the polymeric cement includes a solvent and a polymer. In producing the polymer cement, the solvent includes a polar solvent, a nonpolar solvent, or a mixture thereof. In one or more embodiments, the polar organic solvent is aprotic. An example of a useful aprotic polar organic solvent is tetrahydrofuran (THF). Suitable types of nonpolar organic solvents include, but are not limited to, aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons. Some representative examples of these solvents include n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, isopentane, isohexane, isoheptane, isooctane, 2,2-dimethyl. Butane, petroleum ether, kerosene, light oil, and isomers thereof. Some representative examples of suitable alicyclic solvents include cyclopentane, cyclohexane, methylcyclopentane, methylcyclohexane, and the like. Some representative examples of suitable aromatic solvents include benzene, pyridine, toluene, xylene, ethylbenzene, diethylbenzene, mesitylene, and mixtures of aliphatic, alicyclic and aromatic compounds. Commercial mixtures of the above hydrocarbons such as hexane can also be used.

B. Preparation The polymer cement may be prepared using several techniques. In one embodiment, the cement is prepared by synthesizing the elastomer in an organic solvent. In another embodiment, the cement is prepared by dissolving or suspending the elastomer in an organic solvent. In one or more embodiments, the elastomer is prepared in a nonpolar solvent followed by addition of the polar solvent to a solution of the elastomer in the nonpolar solvent.

  In one or more embodiments, rubbery elastomers can be synthesized by well-known techniques, and the practice of the invention is not limited by the method used to prepare the polymer.

C. Concentration Anyway, polymer cements to which alditol acetals or ketals are added may vary in polymer concentration. In one or more embodiments, the polymer cement is at least 10 wt%, in other embodiments at least 15 wt%, in other embodiments at least 20 wt%, in other embodiments at least 10 wt%, based on the total weight of the cement. It may contain 25% by weight of polymer. In these or other embodiments, the polymer cement is 60 wt% or less, in other embodiments 55 wt% or less, in other embodiments 50 wt% or less, in other embodiments, relative to the total weight of the cement. It may contain up to 45% by weight, in other embodiments up to 40% by weight of polymer.

V. Introduction of alditol acetals or ketals SUMMARY In one or more embodiments, an acetal or ketal of alditol is added directly to the polymer cement. In another embodiment, the acetal or ketal of alditol is premixed with other compounds or solvents and added to the polymer cement as a premix, which can also be referred to as a masterbatch.

  In one or more embodiments, a premix or masterbatch is formed by introducing a solvent capable of dissolving low molecular weight compounds into an acetal or ketal of alditol. For example, THF may be introduced into DBS and dissolved in THF to form a premix that can also be referred to as a masterbatch solution. Other ingredients such as oils and / or compatibilizers may be added to the premix.

B. Conditions In one or more embodiments, the alditol acetal or ketal may be added to the polymer cement while mixing or stirring the polymer cement, and the mixing or stirring is continued after the introduction of the alditol acetal or ketal. May be.

  In one or more embodiments, the introduction of the alditol acetal or ketal may be carried out at atmospheric pressure. In other embodiments, the introduction of the acetal or ketal of alditol is at a pressure of 1.5 atm or higher, in other embodiments 2.0 atm or higher, in other embodiments 3.0 atm or higher, in other embodiments 1 to 4 atm. You may do it below. In these or other embodiments, the introduction is performed while the cement is at a temperature of about 30 to about 130 ° C, in other embodiments about 40 to about 120 ° C, and in other embodiments about 50 to about 100 ° C. Also good. In one or more embodiments, the cement is maintained within these temperature ranges during additional steps and optionally during mixing or stirring.

C. Amount In one or more embodiments, the amount of alditol acetal or ketal added to the polymer cement is at least 0.5 parts by weight (phr) relative to 100 parts by weight of the polymer (phr), in other embodiments at least 1 0.0 pbw, in other embodiments at least 1.5 pbw, in other embodiments at least 2.0 pbw. In these or other embodiments, the amount of alditol acetal or ketal added to the polymer cement is 5.0 pbw or less in phr, 4.5 pbw or less in other embodiments, and 4.0 pbw or less in other embodiments. There may be.

VI. Polymer Separation In one or more embodiments, after introduction of the alditol acetal or ketal to the cement, the polymer and at least a portion of the alditol acetal or ketal are separated from or substantially separated from the solvent. In certain embodiments, the separated product is further dried. Conventional means for desolvation and drying can be used. In one embodiment, the polymer and the acetal or ketal of alditol may be separated from the solvent by vapor desolvation. Residual water may be removed by oven drying. Alternatively, the solvent may be removed using conventional drying techniques such as a drum dryer. Alternatively, the solvent can be removed by evaporation.

VII. Product Features The polymer product produced according to one or more embodiments of the present invention is characterized by favorable cold flow resistance. This favorable cold flow resistance is at least a 10% increase in cold flow by gravity, in other embodiments an increase of at least 20%, etc., compared to similar polymer compositions that do not contain an acetal or ketal of alditol. At least 30% increase in other embodiments, at least 40% increase in other embodiments, at least 80% increase in other embodiments, at least 100% increase in other embodiments, at least 500 in other embodiments % Increase, in other embodiments an increase of at least 1000%, where the cold flow resistance is determined using the gravity analysis described above.

  The polymer product produced by one or more embodiments of the present invention is characterized by favorable cold flow resistance. This favorable cold flow resistance is at least a 10% increase in cold flow by gravity, in other embodiments an increase of at least 20%, etc., compared to similar polymer compositions that do not contain an acetal or ketal of alditol. In other embodiments, at least 30% increase, in other embodiments at least 40% increase, in other embodiments at least 80% increase, in other embodiments at least 100% increase, in other embodiments at least 200% % Increase, in other embodiments an increase of at least 300%, where the accelerated cold flow resistance was determined using the Scott Tester and analysis described above.

VIII. Use of Polymer In one or more embodiments, a polymer composition made according to the present invention may be used to prepare a vulcanizable composition. In preparing the appropriate vulcanizable composition, the polymer may be mixed with other ingredients such as fillers well known in the rubber compounding art.

  The rubber composition may contain fillers such as inorganic and organic fillers. Examples of the organic filler include carbon black. Inorganic fillers include silica, aluminum hydroxide, magnesium hydroxide, clay (hydrated aluminum silicate) and mixtures thereof.

A number of rubber vulcanizing agents can be used. For example, sulfur or peroxide based vulcanization systems can be used. Also Kirk-Othmer, ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, 3 ^rd Edition, Wiley Interscience, NY 1982, Vol. 20, pp. 365-468, especially VULCANIZATION AGENTS AND AUXILIARY MATERIALS pp. 390-402 or Vulcanization by AY Coran, ENCYCLOPEDIA OF ^{POLYMER SCIENCE aND ENGIMEERING, 2 nd Edition} , John Wiley & Sons, Inc., see 1989. These documents are incorporated herein by reference. Vulcanizing agents may be used alone or in combination.

  Other ingredients that can be used include accelerators, oils, waxes, scorch inhibitors, processing aids, zinc oxide, adhesive resins, reinforcing resins, fatty acids such as stearic acid, peptizers, and one or more. Of additional rubber.

  Fillers are typically used in amounts of about 1 to about 100 phr, preferably about 20 to about 90 phr, more preferably about 35 to about 80 phr, where phr is 100% of the rubber in the formulation. Refers to parts by weight of component relative to parts by weight, and the rubber can include any of the additional rubbers that may be added in the blending in addition to the rubber in the premix.

  A vulcanizable rubber composition may be prepared by forming an initial masterbatch containing the premix and filler. This initial masterbatch may be mixed at an onset temperature of about 25 ° C. to about 100 ° C. and an exhaust temperature of about 135 ° C. to about 180 ° C. To prevent premature vulcanization (also known as scorch), this initial masterbatch may not contain a vulcanizing agent. Once the first masterbatch has been processed, the vulcanizing agent can be introduced and mixed in the first masterbatch at a low temperature in a final mixing stage that does not initiate the vulcanization process. Optionally, an additional mixing stage, also referred to as re-kneading, can be employed between the masterbatch mixing stage and the final mixing stage. Rubber compounding techniques and additives used therein are generally known as described in The Compounding and Vulcanization of Rubber, by Stevens in RUBBER TECHNOLOGY SECOND EDITION (1973 Van Nostrand Reinhold Company). Mixing conditions and procedures applicable to silica filled tire formulations are also described in US Pat. Nos. 5,227,425; 5,719,207, 5,717,022 and European Patent No. 0890606. Are well known and are incorporated herein by reference in their entirety.

  When vulcanizable rubber compositions are used in the manufacture of tires, these compositions may be processed into tire components according to conventional tire manufacturing techniques including standard rubber molding, molding and vulcanization techniques. it can. Typically, vulcanization is performed by heating the vulcanizable composition in the mold, for example, heating to about 170 ° C. Vulcanized or crosslinked rubber compositions can be referred to as vulcanizates and generally comprise a thermoset three-dimensional polymer network. Other ingredients such as processing aids and fillers are generally uniformly distributed throughout the vulcanized network. As a component of the tire of the present invention, a tire tread is preferably used. However, other rubbery tire components such as sub-treads, sidewalls, body price kims, bead fillers, etc. can be formed using the rubber composition. Pneumatic tires can be manufactured as described in US Pat. Nos. 5,866,171, 5,876,527, 5,931,211 and 5,971,046. These documents are incorporated herein by reference.

  Also, the vulcanizable rubber composition produced according to the present invention can be used for the production of other rubber articles. For example, the vulcanizable rubber composition can be used in the manufacture of rubber air springs, which are vibration damping devices typically used in trucks. The rubber composition can also be used in the manufacture of rubber sheeting and other articles used to manufacture roofing materials. Moreover, this rubber composition can be used for manufacture of a hose.

IX. Alternative Embodiments In another embodiment, known compounds as organogelators can be used to improve the cold flow properties of an elastomer without adversely affecting the properties and use of the elastomer. These polymer compositions are advantageously produced, but advantageously exhibit similar vulcanization properties, similar Mooney viscosities, and similar kinetic properties as polymer compositions that do not contain an organogelator. As is known in the art, organic gelling agents include various chemical interactions and physical changes either with and / or with organic solvents that alter the liquid properties of organic solvents. The compound which forms gelatin by interaction is mentioned. In certain embodiments, it is believed that certain organic gelling agents interact to form a network or domain within the elastomer that is treated with the organic gelling agent. These networks may be self-organizing networks and may be separate, continuous or semi-continuous. In certain embodiments, these networks are believed to be formed by hydrogen bonding or by π stacking of certain substituents on the compound.

  The practice of this embodiment is not necessarily limited by the use of an organogelator. Thus, elastomers treated with organogelators exhibit low resistance to cold flow and therefore technical problems during storage and transport, as described in connection with previous embodiments. Similar polymers are mentioned. Similarly, the method of introducing the organogelator into the elastomer may be similar to that described in connection with the previous embodiment. For example, an organic gelling agent may be added to the polymer cement containing the elastomer, and the elastomer can be separated from the solvent together with the organic gelling agent. Moreover, the same amount of organic gelling agent can be used. For example, the amount of organogelator added to the polymer cement is at least 0.5 parts by weight (phr) per 100 parts by weight polymer (phr), in other embodiments at least 1.0 pbw, in other embodiments It may be at least 1.5 pbw and in other embodiments at least 2.0 pbw. In these or other embodiments, the amount of organogelator added to the polymer cement is 5.0 pbw or less in phr, 4.5 pbw or less in other embodiments, and 4.0 pbw or less in other embodiments. May be. These polymer compositions exhibiting improved cold flow can be advantageously used in the manufacture of tires as described above in connection with the first embodiment.

  In order to demonstrate the practice of the present invention, the following examples have been prepared and tested. However, these examples do not limit the scope of the present invention. The invention is defined by the claims.

Sample 1-3
A polymer cement containing 18% by mass of styrene-butadiene copolymer rubber (SBR) in THF was prepared. SBR was prepared by an anionic polymerization technique using n-butyllithium initiator and isopropanol (IPA) as a terminator, thereby producing unfunctionalized SBR. GPC analysis of SBR showed 88 kg / mol Mn and 1.1 or less Mn / Mw.

  Dibenzylidene sorbitol (DBS) was optionally added to the polymer cement in the amounts shown in Table 1. The SBR was then separated and subjected to a frequency and temperature sweep using a rheometer. The frequency sweep (2% strain) data showed an increase in the kinetic viscosity of SBR with 1.5 and 3 wt% DBS showing improved cold flow resistance, as shown in FIG. A temperature sweep for the same sample showed an increase in the flow temperature (G ″ ≧ G ′) of DBS containing SBR. An RPA stress relaxation experiment with 100% strain of the polymer showed no improvement in cold flow resistance of DBS-containing SBR (FIG. 2). This data shows that the cold flow resistance of DBS containing polymers is strain dependent. Table 1 also shows the flow temperature where G ′ = G ″.

Sample 4-13
Ten additional polymer cements were prepared by a procedure similar to that used in Sample 1-3. The polymer was anionically polymerized using n-butyllithium as an initiator and stopped using various stoppers as shown in Table 2. Specifically, 3 polymers were terminated with IPA, 3 samples were terminated with 2- (methylthio) -2-thiazoline (thiazoline), and 3 samples were terminated with N, N-dimethylimidazolidinone (DMI). Stopped. Similar to Sample 1-3, a polymer solution in 18% THF was prepared and DBS was added in the amounts shown in Table 2.

  After any addition of DBS, the polymer was separated by evaporating the solvent and tested. In each polymer sample, its cold flow resistance was measured using a Scott tester. In this experiment, each polymer sample (15.5 grams) was melt pressed at 100 ° C. for 20 minutes using a Carver press in an Instron compression mold. After cooling, the sample was removed from the press as a cylindrical shape having a uniform thickness diameter and height of 40.0 mm x 13.0 mm, respectively. The Scott Tester pressed the sample with weight (5000 grams) for 30 minutes and measured the thickness of the polymer sample at 30 minutes.

  As can be seen from the data in Table 3, the addition of DBS to any polymer improved the cold flow compared to the polymer containing no DBS. SBR whose chain ends are functionalized with thiazoline or DMI show slightly better cold flow resistance than unfunctionalized polymers.

  Moreover, the cold flow measurement by gravity of the polymer sample was also performed. In this experiment, each polymer sample (2.5 grams) was melt pressed at 100 ° C. for 20 minutes using a Carver press in an Instron compression mold. After cooling, the sample was removed from the press as a cylindrical shape with a uniform thickness diameter and height of 13.0 mm. The cold flow test by gravity compressed each sample for 28 days at room temperature using the 11.4 g weight used to mimic the weight of a 6 bale stack of polymers. This test revealed that, similar to the Scott tester, the functionalized and non-functionalized polymers have improved cold flow resistance that is superior to polymers that do not contain DBS.

Formulation 4-13
A polymer prepared in Sample 4-13 and optionally treated with DBS was used to produce a carbon black-filled rubber formulation similar to that conventionally used to produce tire treads. Table 4 shows the formulation of the rubber formulation.

The rubber formulation was molded into a sheet and vulcanized according to conventional techniques. The Mooney viscosity (ML _{1 + 4} ) of the unvulcanized formulation was determined at 130 ° C. using an Alpha Technologies Mooney viscometer using a large rotor, 1 minute warm-up time and 4 minutes running time. The breaking strength (Tb) and breaking elongation (Eb) were determined according to ASTM D412. The vulcanized Pain effect data (ΔG ′) and hysteresis data (tan δ) were obtained from dynamic strain sweep experiments conducted at 50 ° C., 15 Hz, and 0.1% to 14.25% strain sweep. . ΔG ′ is the difference between G ′ at 0.1% strain and G ′ at 14.25% strain. The physical properties of the vulcanizates are summarized in Table 5.

  It can be seen that addition of DBS to SBR does not change the properties of the vulcanizate. Compound Mooney viscosity and vulcanization rheometer data suggest that there is a similar processing capability between the DBS containing sample and the coupled sample 13. Similarly, the elongation at break and modulus data are the same as in Sample 13. As can be seen from the data in Table 5, the DBS-containing functionalized SBR has a hysteresis loss similar to the coupled polymer of Sample 13 and G 'values at 0, 30 and 60 ° C. The addition of DBS is not considered to affect the interaction between functional end groups and carbon black.

  Various modifications and alterations that do not depart from the scope and spirit of the invention will be apparent to those skilled in the art. The present invention is not limited to the exemplary embodiments described herein.

Claims (5)

A method for producing a polymer composition comprising:
i) preparing a polymer cement comprising a polymer and a solvent;
ii) introducing an acetal or ketal of alditol into the polymer cement;
iii) separating at least a portion of the polymer and alditol acetal or ketal from the solvent to obtain a polymer composition comprising the polymer and alditol acetal or ketal.   The method of claim 1 wherein the polymer comprises a polydiene or a polydiene copolymer.   The method according to claim 2, wherein the introducing step comprises introducing an acetal of alditol into the polymer cement. A method for producing a polymer composition comprising:
i) preparing a polymer cement;
and ii) introducing dibenzylidene sorbitol into the polymer cement. i) with elastomer
ii) A polymer composition comprising an acetal or ketal of alditol.

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